U.S. Pat. No. 4,821,756 (hereinafter called “Prior Art”) disclosed a collapsible disposable umbrella formed with plastic, polyethylene, etc.
Reviewing the prior art (FIGS. 14 and 17), the rib assembly (80) consisting of rib (26) and strut (32) is cast as a single unit. Each rib assembly (80) includes an upper hook (84) inserted into an upper hub member (38) and a lower hook (94) inserted into a lower hub member (34). So, a plurality of rib assemblies (80) should be provided for assembling the umbrella. Each rib assembly (80) requires a processing work for inserting the hooks (84, 94) into the hub members (38, 34), thereby increasing the assembly procedures and increasing the production cost when forming the umbrella.
The present inventor has found the drawbacks of the prior art, and invented the present environmentally protective umbrella as economically constructed.